1. Field of the Invention
This invention relates to an IP telephone system, an IP telephone apparatus, and a method for identifying a destination user.
2. Description of Related Art
Recently, in addition to the rapid growth of the internet, attention has been directed towards both calling a phone apparatus located at a remote location at a low cost and an IP telephone system in which free calls can be made between registered users who have IP telephone apparatuses. In this kind of IP telephone system, an IP telephone system in which the user's convenience is increased via implementation of a screen display when a call is received or by specifying a ring tone from the calling side is being proposed (for example, see Related Art 1).
Meanwhile, currently, attention is being directed to ENUM as a technology that efficiently manages the information that is used by various communication methods such as telephones, faxes, cell phones or e-mails and enables communications according to the usage environment. ENUM identifies the service over the internet with a unique global identification number that is represented by the E.164 number by using the DNS (Domain Name System). Currently, standardization activity is being carried out by the IETF (Internet Engineering Task force), and thus the protocols to be used are currently being discussed (for example, see Publication 1).
[Related Art 1]Japanese Laid Open Publication 2003—188992[Publication 1]Issued by ENUM Trial Japan “ENUM Trial Japan FirstReport” May, 2004
However, in the above-noted conventional IP telephone system, the display of a screen display corresponding to the caller upon receiving a call or the specifying of a ring tone can only be done from the caller side, and so responses to the usage environment of the receiving side cannot be specified.
Traditionally, in an IP telephone apparatus that is set up within a household or within a company, a plurality of users share the apparatus. In the commonly used IP telephone apparatus, when a user answers an incoming phone call for a different user, it is necessary for the other user to be contacted and the phone call must also be forwarded. In this kind of a usage environment, since it is possible to determine the intended user before the phone call is taken, the process of forwarding the incoming phone call can be omitted, and the user's convenience increases.